On-machine laser spot diagnostics by scanning linear image sensor for maskless lithography system

Akinori Ohkubo; Jiyoung Chu; Janghwi Lee; Sunghwi Cho; Wondon Joo; Sangwoo Bae

doi:10.1117/12.2631007

3 October 2022 On-machine laser spot diagnostics by scanning linear image sensor for maskless lithography system

Akinori Ohkubo, Jiyoung Chu, Janghwi Lee, Sunghwi Cho, Wondon Joo, Sangwoo Bae

Proceedings Volume 12221, Optical Manufacturing and Testing XIV; 122211B (2022) https://doi.org/10.1117/12.2631007
Event: SPIE Optical Engineering + Applications, 2022, San Diego, California, United States

Conference Poster

Abstract

Maskless lithography (ML2) with a scanning high-density spot array has been applied to pattern writing of flat panel displays (FPDs) and printed circuit boards (PCBs). In a ML2 system, spot array diagnostics is necessary to calibrate spot position deviations to achieve exposure pattern uniformity. However, it takes time for the diagnostic including the throughfocus spot profile measurement of a large number of spots (~ 1M spots). Therefore, a high throughput spot diagnostic system is required. We have proposed an alignment-free, high-throughput and cost-effective diagnostic technique with a scanning linear image sensor. Through-focus spot profiles were reconstructed with through-focus scanning signals and response functions of the image sensor pixels. This technique can realize a cost-effective on-machine spot diagnostic system compared to conventional micro-slit scanning systems. We have demonstrated this spot diagnostic with the proofof- concept system. We have confirmed the feasibility in measurements and achieved a lateral position variance of σ < 0.1 μm, (7% of spot size 1.5 μm), an axial position variance of σ < 0.2 μm, (2% of DOF 10 μm) and a telecentricity variance of σ < 1.0 mrad. These variances are then correlating with the level of positioning variances in the stage repeatability. In addition, we also have demonstrated an estimation of low-order wavefront aberrations with a focal spot profile. This onmachine laser spot diagnostic tool could contribute to improve the pattering quality and monitor the optical performance for various focus-spot laser processing systems.

Citation Download Citation

Akinori Ohkubo, Jiyoung Chu, Janghwi Lee, Sunghwi Cho, Wondon Joo, and Sangwoo Bae "On-machine laser spot diagnostics by scanning linear image sensor for maskless lithography system", Proc. SPIE 12221, Optical Manufacturing and Testing XIV, 122211B (3 October 2022); https://doi.org/10.1117/12.2631007

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